Medical device guidance systems are used in medical applications for the purpose of guiding various types of invasive medical devices, such as aspiration and biopsy needles, endoscopes, etc., towards specific targets within a patient""s body. These guidance systems simplify such procedures and make them safer and quicker to perform. In one example of guiding a biopsy needle using a free-hand method, a position sensor is affixed to the needle allowing the needle""s absolute position in space to be determined. The region of the body in which the biopsy is to take place is imaged by an imaging system, such as ultrasound, CT or MRI. The absolute position of the imaging plane displayed by the imaging system is similarly determined using a position sensor affixed to the imaging apparatus and location techniques similar to that used for the needle. With the position information of the needle and of the imaging plane, the relative position of the needle with respect to the displayed imaging plane can be determined. From the relative position information, the projected or actual needle path is computed and is superimposed in real time on the displayed diagnostic image of the patient. This enables the physician to visualize the projected needle path and plan the biopsy procedure even before the needle is inserted into the body.
The following references relate to needle guidance systems: U.S. Pat. No. 5,647,373 to Paltieli, entitled xe2x80x9cArticulated Needle Guide For Ultrasound Imaging and Method of Using Samexe2x80x9d; PCT Application No. WO 99/27837 to Paltieli et al, entitled xe2x80x9cSystem and Method For Guiding the Movements of a Device to a Target Particularly For Medical Applicationsxe2x80x9d; and U.S. Pat. No. 6,216,029 to Paltieli, entitled xe2x80x9cFree-Hand Aiming of a Needle Guidexe2x80x9d. An exemplary device which permits this type of free hand biopsy procedure is the Ultraguide 1000(trademark) System manufactured by Ultraguide, Inc., located in Denver Colo. The Ultraguide 1000(trademark) connects to an existing ultrasound system and provides a separate display device which superimposes graphical representations of the actual and projected needle trajectories over the ultrasound image.
While such devices provide a valuable diagnostic tool to physicians, they also suffer from inherent inaccuracies and may make invasive procedures of small or odd shaped targets at minimum difficult, if not impossible, to complete.
The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiments described below relate to a diagnostic medical ultrasound system. The system includes an invasive medical device and an ultrasound transducer operative to image a portion of a subject, the portion including a target for the invasive medical device. Further, the system includes a location calculator in communication with the ultrasound transducer and the invasive medical device and operative to determine the relative location of the invasive medical device and the ultrasound transducer. In addition, the system includes an image processor in communication with a display, the ultrasound transducer and the location calculator and operative to compute a first trajectory of the invasive medical device within the portion.
The preferred embodiments further relate to a method of displaying a projected and an actual trajectory of an invasive medical device relative to and within a portion of a subject for use in a diagnostic medical ultrasound system. In one embodiment, the method includes generating an image of the portion utilizing an ultrasound transducer, obtaining location information about the ultrasound transducer and the invasive medical device, computing a first trajectory of the invasive medical device relative to the portion utilizing the location information, and computing a second trajectory of the invasive medical device within the portion utilizing the location information.
Further aspects and advantages of the invention are discussed below in conjunction with the preferred embodiments.